Hey Francois,
Best places for surfing in Ireland are on West Coast such as Donegal (Bundoran, Rossnowlagh etc), Sligo (Easkey, Strandhill etc), Clare (lahinch). Sign up with the surf club at Trinity & they do loads of trips.
Google websites such as Bundoran Surf Co & Turf n Surf.
Also get yourself Stormriders Guide to Europe.
Irish surfers are pretty decent & not aggressive, & welcome foreign visitors!
Good luck!